Syrian government negotiator Bashar al-Ja'afari said an attack by gunmen and suicide bombers on Syrian security offices that killed dozens in Homs on Saturday was a message aimed at the Geneva peace talks and would not be ignored.

"The terrorist explosions that hit Homs city are a message to Geneva from sponsors of terrorism, and we tell everyone that the message is received and this crime won't pass unnoticed," he told reporters before meeting UN envoy Staffan de Mistura.